Method of joining metals



May 29, 1923. 1,456,855

T. MIDGLEY, JR

METHOD OF JOINING METALS Filed ,June 30 1919 Fl .5. F1 J g dZfiZZFsTgss M4 9100.

Patented May 29, 1923.

UNITED STATES PATENT OFFICE.

THoMAs MIDGLEY, JR, or DAYTON, OHIO, ASSIGNOR, ZBY MESNE ASSIGNMENTS, T0 GENERAL MOTORS nnsnnacn conroaa'rrou. or DAYTON, OHIO, A CORPORATION OF DELAWARE.

METHOD OF JOINING METALS.

Application-filed June 30, 1919. Serial NO. 307,640.

T 0 all '2!) 710m. it may concern Be it known that I, Trrouas Mmonnv, Jr., a citizen of the United States of America, residing at Dayton, county of lvlontgomery, State of Ohio, have invented certain new and useful Improvements in Methods of Joining Metals, of which the followlng is a full, clear, and exact description.

This invention relates to the joining dissimilar metals, and more particularly the joining of two metals by means casting.

One of the principal objects of this 1nvention is to provide means for uniting to a metal which has a high co-ellicient of conductivity another metal by casting such last named metal around, or in contact with, the metal of high comluctivity.

Other objects and advantages of the present invention will be. apparent from the description set out below, when taken In connection with the drawings. lVhere two similar metals are to be joined together, such for instance'as iron and steel, it is quite common practice to secure the desired union by incorporating one of the metals in a mold and casting the other in Contact with it. I have found, however, that where it is desired to unite a metal having a high coefiicient of heat conductivity to another metal by casting,.satisfactory results are not readily secured where the conventional casting method is used. If it is desired, for example, to unite copper to cast iron by casting iron around, or in contact with, the copper it is extremely difiicult to'secure a true bonding or union of the two metals by the use of any casting method heretofore known to me. It appears that when copper is incorporated in a mold and molten iron is poured into the mold, and into contact with the copper, there is such a rapid transfer ct heat from the molten iron through the copper that chilling of the iron in contact with the copper results. Consequently a good bond of the copper and iron will probably not result. Thi condition would also obtain with other metals, besides copper, having a high coefficient of heat conductivity.

Where a metal, such as iron, is cast in contact with a metal of high heat conductivity, such as copper, I have t'ound that a good bond of the two metals may be secured if the good conducting metal is of to of heated, before the casting operation, to a temperature approximating the temperature of the molten iron. By thus preheating such metal chilling of the iron which first contacts with it is prevented.

In the drawing herewith is illustrated apparatus for carrying this method into eiiect. The method will be described particularly in connection with theijoining of copper adiating fins to a cast iron engine cylinder, although it is quite obvious that the invention is by no means limited to this specific disclosure.

In the drawing:

Fig. 1 illustrates, what is termed, a former, showing several fins positioned in place preparatory to the making of that part of the mold which contains the copper with which the iron is to be cast in contact;

Fig. 2 is an elevational view of the former and fins which are shown in section in Fig.1;

Fig. 3 shows the former and fins positioned within a core box, sand being shown as tamped in place within the spaces surrounding the fins, preparatory to baking to form a core; Y

Fig. 4. shows a completed core after the assembly shown in Fig. 3 has been baked and the core box and former removed therefrom i Fig. 5 shows a complete mold ready for the casting operation; and

Fig. 6 discloses an engine cylinder, with copper fins, resulting from a casting operation within the mold shown in Fig. 5.

Each of the Figs. 1, 3, 4, 5 and 6 represents a section taken through the apparatus along aline corresponding approximately with that shown in Fi 2.

In carrying out thls method of uniting iron and copper, for example, the joining of copper fins to a cast iron engine cylinder, an assembling member 10, which for convenience is called a former, the dimen sions of which correspond to the dimensions of the cylinder to be cast, is made up, such former being of any desired material, as for instance steel or aluminum. Longitudinal grooves 11 are cut in the outersurface of this former, such grooves being adapted to receive the fins 12 which are to be united to the engine cylinder. The former and fins having been assembled are then placed in a core box 15 and sand 16, or some analogous material, piixed with some bindingnnm teria1,-suc=has linseed oil is-tamped into place around the fins. tampedv into, place the core. box. is thenpreferahlyfv placed} in i, a heating .oven and. baked so that "the sand 16 with the fins 12 forms a hard core, tree from moisture which.is designated generally by the numeral 20, and which is shown clearly in Fig. 4.

The core 20 having been properly prepared thencov-ered over-witha layer of paper,.. orwanalogous. material, .21, which paperis painted orcoated with .somennaterialadaptedto protect certain portions of the copper incorporatednvithini the core. In

actual practice the ecoating for. this paper preferably. comprisesa mixture of graphite and watenglass. The corewith its covering ,21 1 is: then incorporated .in a mold,: the moldv being madeup. in a convenional box 25;. Surroundingthe core isa. plurality of POHIlDgSBClZlOIIS-JQG formed in .the ESZLIKl 27 which constitutes the body of the mold. The purpose of these sections is to .permito-f pouring :molten 1 metal adjacent a the copper elements beforerthe actual; casting. operation so asito preheat the.copp.er toia temperature .approximating the temperature. ,of the.molten metal: to establish a low temperature differential;- betweenthe copper and themolteniiron. Theifunctionof the coated covering 21 is to prevent the metal ,otthe preheatingtsections from. forming a bond with 2the1icopper, the graphite and .water glass .coatingthis .coveringbeing adapted to preuehtsuch bonding. Thesand .of the mold is also preferably mixed with a. binderrand baked,- as is the .ooreQO. Withinv the central opening through. thecore "20is placed. a similarly baked core28. '1Tl'1iS5 core isof such dimensions as to leave a space 29 'adaptedito receiue the zmolten:. metalwhich is to constitute the engine cylinder. .-.'As (is quite evident from the drawingy'theinner endsot the fins 12;:wvhen,incorporatedwithin thezmold extend a snbstantiahdistance .iDtOathis space, andrwhemthemolten ironis poured into the spaceufifliit flowsaaround. these ends of the finsnforming. a; geodhond with. them. In. Fig. 6 is shown a cylinder made byacasting inalmoldsuchas described.

The 2 method of carrying out; this casting operation .is as followscwThezaimis to secure'e 'bondingaof themolten iron .where, it comeswincontact With the metal of :goQdconductivity. or copper, 5 and to secure this desired condition preheat such metal. In the,"mold-shown,this-preheatingis setutes a preferred embodiment of. any 1 invencured ihy first pouring molten iron ,into the preheating-sections, 26. .,This;,ir0n is preventedifrorn adhering to the metal; incorporated withinthe core by means of the covering 29 and its graphite and water glass ,coatingi; nAsufiicient-time is allowed, after Lthis preheating metalq is poured. into place,

Vhen properly .body of the casting. ,In actualpractice the duration of this reheatingperiOd will vary,

from five minutes to teninlnu'tesbei ng generally sufiicient, the length of the period being of course dependent upon the amount of metal to he preheated. The metal having been pr0perly preheated the molted iron is then poured into the space. 29,;the low temperature difierential between the iron and copper being maintained by the members 12 acting to prevent escape'of heat from the copper. .VVhen the mold has cooled down suflicientlyit is broken-away; and the preheating sections removed. The sand. 16 forming the core 20 is also removed and a finished article, such for; instance as illustratedin Fig.6, is left.

.Thisniethodof casting is describedin connection with the casting of engineicyline dershavingiicopper radiating fins thereon. It is quite obviousqthatit is not limited to the malzingof articles of this specific char,- acter. This method of casting may be useful whenever it is desired to cast a metal in contact with another metal having a high coclfieient-.-of heatconductivity Thisiis especially true in the castingo firon around such a metahas theiron hardens upon-chilling. vent a goodbondibutproduces-hams ts within the iron-which make proper mac ining extremely difficult.

; The mold describedebove is one in which the Yal'lOl-IS parts of the mold,.ivith an incorporated bonding material, are baked before casting i- Although this seems. especially desirable in the attachment of ooppenfins This chilling nothonlyfltendsmo .pre-

rily with; the use of other means for preheat- .ing-the metal: of high conductivity. .For example electric heating units might be incorporated Within the core in such wise asv-to permit of preheating such metal: to thedesired temperature- While, the -metho d definedabove constition, that inventionis by no meanszlimited to themrecise disclosure above-set fort-hand It should be noted thatthe present fipplication contains, no broad claims to the article for a tr ledefinition thereof referenceshou-ld be had to the appended claims produced by this process as such claims are being presented in an application filed in the name of C. F. Kettering, Serial No. 354,770, under date of June 29, 1920. The broad claims to a method of producing an engine cylinder in which true thermal contact is had between the fins and the metal of the cylinder, are also being presented in this latter application.

What I claim is as follows:

1. The method of casting iron around a metal which is a good conductor of heat, which comprises preheating said metal within the mold before the casting operation to establish a low temperature differential between the good conducting metal and the casting metal, and substantially maintaining the low temperature differential during the casting operation.

2. The method of casting iron around a metal which is a good conductor of heat; which comprises heating said metal to a temperature approximately the temperature of molten iron to establish a low temperature differential between the good conduct-- ing metal and the casting metal, then casting the iron in contact with such heated metal and substantially maintaining the low temperature differential during the casting operation.

5. The method of casting iron around a metal which is a good conductor of heat; which comprises positioning heating sections in heating relation to such metal; heating said metal to a temperature approximately that of molten iron to establish a low temperature differential between the good conducting metal and the casting metal, then pouring molten iron into contact with such heated metal and substantially maintaining the low temperature differential dur ing the casting operation.

4. The method of uniting copper to iron which comprises incorporating the copper in a mold; preheating the copper to a temperature approximating the temperature of molten iron and pouring molten iron into the mold and into contact with the copper.

5. The method of uniting copper to iron which comprises incorporating the copper in a mold; preheating the copper by means of heating sections within the mold, and in heat transferring relation with the copper; and then pouring molten iron into the mold and in contact with the copper.

6. The method of uniting copper to iron which comprises covering parts of the copper with a material adapted to prevent the adhesion of molten iron to said copper, incorporating such partly covered copper in a mold; pouring molten iron into heat transferring relation with the covered parts of the copper, to heat the copper to a temperature approximating the temperature of the molten iron; and then pouring molten iron into the mold and in actual contact with parts of the copper which are not covered.

7. The method of uniting copper to iron THOMAS MIDGLEY, JR.

\Vitnesses:

J. \V. MoDoNaLn, A. C. LEHMAN. 

